PRLD

SEC source: 0001209191-20-052404 · doc4.xml · derivative · entry 6

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 4,418,186 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052404 · doc4.xml · derivative · entry 5

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 2,196,494 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F5 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F5 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052404 · doc4.xml · derivative · entry 4

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 3,294,743 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052404 · doc4.xml · nonDerivative · entry 3

ORBIMED ADVISORS LLC · CIK 0001055951 · Director · 10% owner

OrbiMed Capital GP VI LLC · CIK 0001682115 · Director · 10% owner

ORBIMED CAPITAL LLC · CIK 0001157524 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 9,250,191

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · ownership.nature: This report on Form 4 is jointly filed by OrbiMed Advisors, OrbiMed Capital GP VI LLC ("GP VI"), and OrbiMed Capital. Each of the Reporting Persons disclaims beneficial ownership of the securities reported herein for purposes of Rule 16a-1(a) under the Exchange Act, except to the extent of its pecuniary interest therein, if any. This report shall not be deemed an admission that any such entity is a beneficial owner of such securities for purpose of Section 16 of the Exchange Act, or for any other purpose. The Reporting Persons have designated a representative, David Bonita, a member of OrbiMed Advisors, to serve on the Issuer's board of directors.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). GP VI is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052403 · doc4.xml · nonDerivative · entry 1

Dier Mardi · CIK 0001574591 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 10,000

SEC source: 0001209191-20-052405 · doc4.xml · nonDerivative · entry 1

Combs Andrew · CIK 0001825005 · EVP, Head of Chemistry

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 260,380

F1 · balance_after: Certain of the shares are subject to forfeiture to the Issuer if underlying vesting conditions are not met.

SEC source: 0001209191-20-052402 · doc4.xml · nonDerivative · entry 1

Morosini Deborah · CIK 0001824625 · EVP, Chief of Clinical Affairs

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 444

SEC source: 0001209191-20-052400 · doc4.xml · nonDerivative · entry 1

Pierce Christopher · CIK 0001824631 · EVP and Chief of Business Oper

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 3,750

SEC source: 0001209191-20-052399 · doc4.xml · derivative · entry 8

Vaddi Krishna · CIK 0001824633 · Director · President, CEO

10b5-1 filing: Not disclosed

Ownership: Indirect · By Trust

Disclosed balance after: 0

Underlying: Common Stock · 32,876 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F2 · derivative.exercise_date: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F2 · derivative.expiration_date: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F5 · ownership.nature: The Reporting Person is the investment advisor of the Brocade Trust. The Reporting Person disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of such securities for purposes of Section 16 or for any other purposes.

SEC source: 0001209191-20-052399 · doc4.xml · derivative · entry 7

Vaddi Krishna · CIK 0001824633 · Director · President, CEO

10b5-1 filing: Not disclosed

Ownership: Indirect · By Trust

Disclosed balance after: 0

Underlying: Common Stock · 32,876 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F2 · derivative.exercise_date: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F2 · derivative.expiration_date: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F4 · ownership.nature: The Reporting Person is the investment advisor of the Blue Sky Trust. The Reporting Person disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of such securities for purposes of Section 16 or for any other purposes.

SEC source: 0001209191-20-052399 · doc4.xml · derivative · entry 6

Vaddi Krishna · CIK 0001824633 · Director · President, CEO

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 0

Underlying: Common Stock · 101,477 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · derivative.exercise_price: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F2 · derivative.exercise_date: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F2 · derivative.expiration_date: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F3 · ownership.nature: The Reporting Person is the manager of Sidus Ventures LLC. The Reporting Person disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of such securities for purposes of Section 16 or for any other purposes.

SEC source: 0001209191-20-052399 · doc4.xml · nonDerivative · entry 4

Vaddi Krishna · CIK 0001824633 · Director · President, CEO

10b5-1 filing: Not disclosed

Ownership: Indirect · By Trust

Disclosed balance after: 551,774

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · price: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F5 · ownership.nature: The Reporting Person is the investment advisor of the Brocade Trust. The Reporting Person disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of such securities for purposes of Section 16 or for any other purposes.

SEC source: 0001209191-20-052399 · doc4.xml · nonDerivative · entry 3

Vaddi Krishna · CIK 0001824633 · Director · President, CEO

10b5-1 filing: Not disclosed

Ownership: Indirect · By Trust

Disclosed balance after: 551,776

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · price: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F4 · ownership.nature: The Reporting Person is the investment advisor of the Blue Sky Trust. The Reporting Person disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of such securities for purposes of Section 16 or for any other purposes.

SEC source: 0001209191-20-052399 · doc4.xml · nonDerivative · entry 2

Vaddi Krishna · CIK 0001824633 · Director · President, CEO

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnote

Disclosed balance after: 101,477

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · price: The Series A Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F3 · ownership.nature: The Reporting Person is the manager of Sidus Ventures LLC. The Reporting Person disclaims beneficial ownership of such securities except to the extent of his pecuniary interest therein, and the inclusion of these securities in this report shall not be deemed an admission of beneficial ownership of such securities for purposes of Section 16 or for any other purposes.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 31

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 5,058,149

Underlying: Common Stock · 382,884 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F14 · derivative.exercise_price: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F14 · derivative.exercise_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F14 · derivative.expiration_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F12 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 30

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 382,884 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F14 · derivative.exercise_price: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F14 · derivative.exercise_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F14 · derivative.expiration_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F12 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 29

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 497,036

Underlying: Common Stock · 30,349 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F14 · derivative.exercise_price: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F14 · derivative.exercise_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F14 · derivative.expiration_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F11 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 28

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 30,349 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F14 · derivative.exercise_price: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F14 · derivative.exercise_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F14 · derivative.expiration_date: Series C Preferred automatically converted at the Series C Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series C Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F11 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 27

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 574,327 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · derivative.exercise_price: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F7 · derivative.exercise_date: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F7 · derivative.expiration_date: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 26

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 45,524 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · derivative.exercise_price: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F7 · derivative.exercise_date: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F7 · derivative.expiration_date: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 25

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 4,675,265

Underlying: Common Stock · 2,698,424 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F13 · derivative.exercise_price: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F13 · derivative.exercise_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F13 · derivative.expiration_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F12 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 24

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 2,698,424 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F13 · derivative.exercise_price: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F13 · derivative.exercise_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F13 · derivative.expiration_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F12 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 23

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 466,687

Underlying: Common Stock · 247,034 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F13 · derivative.exercise_price: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F13 · derivative.exercise_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F13 · derivative.expiration_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F11 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 22

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 247,034 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F13 · derivative.exercise_price: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F13 · derivative.exercise_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F13 · derivative.expiration_date: Series B Preferred automatically converted at the Series B Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into Non-Voting Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series B Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F11 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 21

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 4,047,634 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · derivative.exercise_price: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F6 · derivative.exercise_date: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F6 · derivative.expiration_date: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 20

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 370,552 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · derivative.exercise_price: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F6 · derivative.exercise_date: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F6 · derivative.expiration_date: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 19

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 1,976,841

Underlying: Common Stock · 1,976,841 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F10 · derivative.exercise_price: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F10 · derivative.exercise_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F10 · derivative.expiration_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F12 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 18

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 1,976,841 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F10 · derivative.exercise_price: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F10 · derivative.exercise_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F10 · derivative.expiration_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F12 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 17

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 219,653

Underlying: Common Stock · 219,653 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F10 · derivative.exercise_price: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F10 · derivative.exercise_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F10 · derivative.expiration_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F11 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 16

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 219,653 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F10 · derivative.exercise_price: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F10 · derivative.exercise_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F10 · derivative.expiration_date: Series A Preferred automatically converted at the Series A Preferred Conversion Ratio without payment or further consideration immediately prior to the close of the IPO into non-voting common stock of the Issuer ("Non-Voting Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Non-Voting Common Stock shown in column 7 of Table II. The Series A Preferred had no expiration date. Each share of Non-Voting Common Stock is convertible into one share of Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days notice to the Issuer.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F11 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the securities reported in column 7 of Table II directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 15

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 2,965,263 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_price: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F3 · derivative.exercise_date: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F3 · derivative.expiration_date: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · derivative · entry 14

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 0

Underlying: Common Stock · 329,478 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · derivative.exercise_price: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F9 · price: Pursuant to Instruction 4(c)(iii), this response has been left blank.

F3 · derivative.exercise_date: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F3 · derivative.expiration_date: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 8

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 9,247,763

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F8 · ownership.nature: 667 and Life Sciences purchased 104,628 and 1,474,319 shares of Common Stock, respectively, for $19.00 per share pursuant to the IPO that closed on September 29, 2020.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 7

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 870,873

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F8 · ownership.nature: 667 and Life Sciences purchased 104,628 and 1,474,319 shares of Common Stock, respectively, for $19.00 per share pursuant to the IPO that closed on September 29, 2020.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 6

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 7,773,444

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · price: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F7 · ownership.nature: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 5

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 766,245

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F7 · price: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F7 · ownership.nature: Series C Convertible Preferred Stock ("Series C Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series C Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series C Preferred had no expiration date.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 4

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 7,199,117

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · price: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

F6 · ownership.nature: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 3

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 720,721

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F6 · price: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

F6 · ownership.nature: Series B Convertible Preferred Stock ("Series B Preferred") of the Issuer automatically converted on a 1-for-1 basis ("Series B Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the IPO into Common Stock. The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series B Preferred had no expiration date.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 2

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 3,151,483

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · price: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F3 · ownership.nature: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F5 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Brothers Life Sciences Capital L.P. and (ii) Life Sciences, Felix J. Baker and Julian C. Baker may be deemed to have an indirect pecuniary interest in Common Stock reported in column 5 of Table I beneficially owned by Life Sciences, a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital, L.P., a limited partnership of which the sole general partner is Baker Brothers Life Sciences Capital (GP), LLC, due to their interest in Life Sciences and Baker Brothers Life Sciences Capital, L.P.'s right to receive an allocation of a portion of the profits from Life Sciences.

SEC source: 0001638599-20-000842 · doc4_6886.xml · nonDerivative · entry 1

BAKER BROS. ADVISORS LP · CIK 0001263508 · Director · 10% owner

667, L.P. · CIK 0001551139 · Director · 10% owner

Baker Bros. Advisors (GP) LLC · CIK 0001580575 · Director · 10% owner

Baker Brothers Life Sciences LP · CIK 0001363364 · Director · 10% owner

BAKER FELIX · CIK 0001087940 · Director · 10% owner

BAKER JULIAN · CIK 0001087939 · Director · 10% owner

Joint disclosure: these amounts are not allocated separately to each reporting owner.

10b5-1 filing: Not disclosed

Ownership: Indirect · See Footnotes

Disclosed balance after: 350,169

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F3 · price: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F1 · ownership.nature: Baker Bros. Advisors LP (the "Adviser") serves as the investment adviser to 667, L.P. ("667") and Baker Brothers Life Sciences, L.P. ("Life Sciences", and together with 667, the "Funds"). In connection with the services provided by the Adviser, the Adviser receives an asset-based management fee that does not confer any pecuniary interest in the securities held by the Funds. Baker Bros. Advisors (GP) LLC (the "Adviser GP") is the Adviser's sole general partner. Julian C. Baker and Felix J. Baker are managing members of the Adviser GP. The Adviser has complete and unlimited discretion and authority with respect to the investment and voting power of the securities held by the Funds. The general partners of the Funds relinquished to the Adviser all discretion and authority with respect to the investment and voting power of the securities held by the Funds.

F2 · ownership.nature: Julian C. Baker, Felix J. Baker, the Adviser GP and the Adviser disclaim beneficial ownership of the securities held directly by the Funds except to the extent of their pecuniary interest therein, and this report shall not be deemed an admission that any of Julian C. Baker, Felix J. Baker, the Adviser GP or the Adviser is a beneficial owner of such securities for purposes of Section 16 or any other purpose.

F3 · ownership.nature: Series A Convertible Preferred Stock ("Series A Preferred") of Prelude Therapeutics Incorporated (the "Issuer") automatically converted on a 1-for-1 basis ("Series A Preferred Conversion Ratio") without payment or further consideration immediately prior to the close of the Issuer's initial public offering ("IPO") into voting common stock of the Issuer ("Common Stock"). The Funds elected to automatically convert immediately prior to the IPO into the number of shares of Common Stock shown in column 5 of Table I. The Series A Preferred had no expiration date.

F4 · ownership.nature: After giving effect to the transaction reported herein and as a result of their ownership interest in (i) Baker Biotech Capital, L.P. and (ii) 667, Julian C. Baker and Felix J. Baker each may be deemed to have an indirect pecuniary interest in the Common Stock reported in column 5 of Table I directly held by 667, a limited partnership of which the sole general partner is Baker Biotech Capital, L.P., a limited partnership of which the sole general partner is Baker Biotech Capital (GP), LLC, due to their interest in 667 and Baker Biotech Capital, L.P.'s right to receive an allocation of a portion of the profits from 667.

SEC source: 0001209191-20-052517 · doc4.xml · derivative · entry 13

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 5,555,186

Underlying: Common Stock · 5,555,186 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F8 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · derivative.underlying_shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · derivative.underlying_shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052517 · doc4.xml · derivative · entry 12

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 413,234 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F8 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · derivative.underlying_shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · derivative.underlying_shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052517 · doc4.xml · derivative · entry 11

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 619,850 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · derivative.underlying_shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · derivative.underlying_shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052517 · doc4.xml · derivative · entry 10

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 2,945,458 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F8 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · derivative.underlying_shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · derivative.underlying_shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052517 · doc4.xml · derivative · entry 9

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 4,418,186 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · derivative.underlying_shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · derivative.underlying_shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052517 · doc4.xml · derivative · entry 8

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Non-Voting Common Stock · 2,196,494 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F8 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F8 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Non-Voting Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date. Each share of the Issuer's Non-Voting Common Stock is convertible into one share of the Issuer's Common Stock at any time at the option of the holder without consideration subject to a 9.99% beneficial ownership limitation which may be increased or decreased by the holder upon 61 days' notice to the Issuer.

F2 · derivative.underlying_shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · derivative.underlying_shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052517 · doc4.xml · derivative · entry 7

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 0

Underlying: Common Stock · 3,294,743 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F4 · derivative.exercise_price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.exercise_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F4 · derivative.expiration_date: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · derivative.underlying_shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · derivative.underlying_shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052517 · doc4.xml · nonDerivative · entry 3

Bonita David P · CIK 0001572451 · Director · 10% owner

10b5-1 filing: Not disclosed

Ownership: Indirect · See footnote

Disclosed balance after: 9,250,191

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F2 · shares: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · shares: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

F4 · price: Each share of the Issuer's Series A Preferred Stock, Series B Preferred Stock, and Series C Preferred Stock automatically converted into one share of the Issuer's Common Stock immediately prior to the closing of the Issuer's initial public offering and has no expiration date.

F2 · ownership.nature: The Reporting Person is a member of OrbiMed Advisors. This report shall not be deemed an admission that any of the Reporting Person, OrbiMed Advisors, OrbiMed Capital or GP VI is a beneficial owner of such securities for the purpose of Section 16 of the Exchange Act, or for any other purpose.

F3 · ownership.nature: These securities are held of record by OrbiMed Private Investments VI, L.P. ("OPI VI"). OrbiMed Capital GP VI LLC ("GP VI") is the general partner of OPI VI and OrbiMed Advisors is the managing member of GP VI. The Reporting Person is a member of OrbiMed Advisors. By virtue of such relationships, GP VI and OrbiMed Advisors may be deemed to have voting power and investment power over the securities held by OPI VI and as a result, may be deemed to have beneficial ownership over such securities. OrbiMed Advisors exercises voting and investment power through a management committee comprised of Carl L. Gordon, Sven H. Borho, and Jonathan T. Silverstein, each of whom disclaims beneficial ownership of the shares held by OPI VI.

SEC source: 0001209191-20-052518 · doc4.xml · derivative · entry 5

FRIEDMAN PAUL A · CIK 0001236927 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 152,576 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series A and Series B Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F1 · derivative.exercise_date: The Series A and Series B Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F1 · derivative.expiration_date: The Series A and Series B Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

SEC source: 0001209191-20-052518 · doc4.xml · derivative · entry 4

FRIEDMAN PAUL A · CIK 0001236927 · Director

10b5-1 filing: Not disclosed

Ownership: Direct

Disclosed balance after: 0

Underlying: Common Stock · 295,794 shares

Expires not disclosed

Exercise/conversion can include RSU settlement. Transaction price and option strike are different fields; a missing price is not zero. Derivative and underlying rows can describe the same event.

F1 · derivative.exercise_price: The Series A and Series B Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F1 · derivative.exercise_date: The Series A and Series B Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.

F1 · derivative.expiration_date: The Series A and Series B Preferred Stock automatically converted into shares of the Issuer's common stock on a one-for-one basis immediately upon the closing of the Issuer's initial public offering on September 29, 2020 and had no expiration date.